Method for measuring refractive power and apparatus therefor

ABSTRACT

A refractive power measuring method is disclosed wherein a pattern plate  8  is disposed at a certain position in a measuring optical path in a measuring optical system  1 , a measuring light emitted from a measuring light source  5  is received by a photosensor  9  through the pattern plate  8 , a soft contact lens TL is disposed at a certain position in the measuring optical path, and a change of a pattern light received by the photosensor  9  is obtained to determine optical characteristic values of the soft contact lens. According to this method, the soft contact lens TL is disposed in a wet state at a certain position of the measuring optical path and scattered light resulting from scatter of the measuring light on a surface of the soft contact lens TL is received by the photosensor  9 , then a state of scatter of the scattered light is determined from a change of a received light signal outputted from the photosensor  9  and there are obtained optical characteristic values when the received light signal is below a preset value.

TECHNICAL FIELD

The present invention relates to a refractive power measuring method andapparatus able to measure optical characteristic values of a softcontact lens precisely in air.

BACKGROUND ART

Heretofore, it has been known that a soft contact lens is softer than ahard contact lens and that when a soft contact lens is subjected tomeasurement while being held on a lens receiving plate in air, the shapethereof is apt to be deformed by its own weight.

Besides, a large amount of water is contained in the soft contact lens,so if the soft contact lens is allowed to stand in air for a long time,the water contained therein will evaporate. Consequently, if opticalcharacteristics of the soft contact lens are measured in air by means ofa lens meter, an error is apt to occur in measured values. To avoid thisinconvenience, both skill and rapidness of measurement are required forthe measurement of a soft contact lens.

To meet this requirement, a lens meter is being developed which measuresoptical characteristic values of a soft contact lens while dipping thecontact lens in liquid to retain the shape thereof.

Since this lens meter can measure optical characteristic values whileretaining the shape of a soft contact lens and without evaporation ofwater, skill is not so strictly required, nor is required so highrapidness, in the measurement.

However, optical characteristic values of a soft contact lens measuredin liquid and those measured in air are different. In more particularterms, when measurement is made in liquid, the difference between therefractive index of a soft contact lens and that of the liquid issmaller than the difference between the refractive index of the softcontact lens and that of air. Consequently, optical characteristicvalues of a soft contact lens measured in liquid are smaller than thoseof the same contact lens measured in air.

Therefore, when optical characteristic values of a soft contact lens aremeasured in liquid, it is necessary to convert them into opticalcharacteristic values in air, and the refractive index of the materialof the soft contact lens is needed for the said conversion.

However, the refractive index of the material of a soft contact lens isunknown in many cases, so it is impossible to make conversion fromoptical characteristic values of a contact lens measured in liquid intooptical characteristic values thereof in air which are opticalcharacteristic values obtained when the contact lens is applied to aneye, and there exists a problem that converted optical characteristicvalues obtained by the conversion of optical characteristic values of acontact lens measured in liquid are poor in reliability.

The present invention has been accomplished in view of theabove-mentioned circumstances and it is an object of the invention toprovide a refractive power measuring method and apparatus able tomeasure optical characteristic values of a soft contact lens preciselyin air.

DISCLOSURE OF INVENTION

For achieving the above-mentioned object, in one aspect of the presentinvention there is provided a refractive power measuring method forobtaining optical characteristic values of a soft contact lens,characterized in that when the contact lens is disposed in a wet statein air and at a certain position in a measuring optical path, scatteredlight from the soft contact lens is received by a light receivingelement, then a state of scatter of the scattered light is detected froma change of a received light signal outputted from the light receivingelement which receives the scattered light, and the opticalcharacteristic values are obtained when the received light signalsatisfies a predetermined condition.

In another aspect of the present invention there is provided arefractive power measuring apparatus for obtaining opticalcharacteristic values of a soft contact lens, comprising:

a light receiving element which receives scattered light from the softcontact lens when the soft contact lens is disposed in a wet state inair and at a certain position in a measuring optical path; and

a calculation means which calculates the optical characteristic valueswhen a received light signal outputted from the light receiving elementsatisfies a predetermined condition.

In a further aspect of the present invention there is provided arefractive power measuring apparatus comprising:

a measuring optical system including a pattern light forming meansdisposed at a certain position in a measuring optical path extendingfrom a light source to a light receiving element, a measuring light fromthe light source being made into a pattern light by the pattern lightforming means and the pattern light being received by the lightreceiving element; and

an arithmetic and control circuit which, when a soft contact lens isdisposed at a certain position in the measuring optical path, determinesa change of the pattern light received by the light receiving elementfrom a change of a received light signal outputted from the lightreceiving element, thereby obtaining optical characteristic values ofthe soft contact lens disposed at a certain position in the measuringoptical path,

wherein a scattered light receiving portion for receiving scatteredlight and outputting a received scattered light signal is providedseparately from the light receiving element, the scattered light beinggenerated when the measuring light passes through the soft contact lens,and

the arithmetic and control circuit determines the optical characteristicvalues from the received light salt when the received scattered lightsignal is below a preset value from the time when the soft contact lensis set in a wet state onto a lens rest and measurement is started.

In a still further aspect of the present invention there is provided arefractive power measuring apparatus comprising:

a measuring optical system which projects a measuring light on a softcontact lens set on a lens rest and wet with liquid;

a light receiving optical system having a light receiving means forreceiving the measuring light which has passed through the soft contactlens; and

a calculation means which calculates optical characteristics of the softcontact lens at every predetermined time in accordance with an outputsignal provided from the light receiving means;

wherein there is provided a decision means which determines correctoptical characteristics of the liquid-wet soft contact lens from a timeseries of optical characteristics calculated by the calculation means.

In a still further aspect of the present invention there is provided arefractive power measuring apparatus comprising:

a measuring optical system which projects a measuring light onto a softcontact lens set on a lens rest and wet with liquid;

a light receiving optical system having a light receiving means forreceiving the measuring light which has passed through the soft contactlens; and

a calculation means which calculates optical characteristics of the softcontact lens at every predetermined time in accordance with an outputsignal provided from the light receiving means,

wherein there are provided:

a storage means which stores in time series the optical characteristicscalculated by the calculation means; and

a decision means for determining correct optical characteristics of theliquid-wet soft contact lens from the optical characteristics stored intime series in the storage means.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an optical system of a lens meter as an example of anapparatus for measuring optical characteristics of a contact lensaccording to a first embodiment of the present invention, as well as anassociated processing circuit in terms of a block diagram;

FIG. 2 is a plan view of a pattern plate shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a relation between aphotosensor shown in FIG. 1 and an aperature pattern image;

FIG. 4 illustrates exaggeratedly how a surface state of a soft contactlens associated with the present invention changes, in which (a) shows awet state of the soft contact lens with a large amount of liquid, (b)shows a state in which the soft contact lens is wet with an appropriateamount of liquid and the surface thereof in smooth, and (c) shows astate in which the soft contact lens is dry and the surface thereof isrough;

FIG. 5 is an explanatory diagram showing a relation between thephotosensor shown in FIG. 1 and an aperture pattern image inmeasurement;

FIG. 6 is an explanatory diagram showing a relation between thephotosensor shown in FIG. 1 and another aperture pattern image inmeasurement;

FIG. 7(a) is an explanatory diagram of a measuring light beam in thepresence of scattered light and FIG. 7(b) is an explanatory diagram ofan output of the photosensor based on the measuring light beam shown inFIG. 7(a);

FIG. 8(a) is an explanatory diagram of a measuring light beam in thepresence of scattered light and FIG. 8(b) is an explanatory diagram ofan output of the photosensor based on the measuring light beam shown inFIG. 8(a);

FIG. 9(a) is an explanatory diagram of a measuring light beam in thepresence of scattered light and FIG. 9(b) is an explanatory diagram ofan output of the photosensor based on the measuring light beam shown inFIG. 9(a);

FIG. 10 is an explanatory diagram showing photosensor outputs in FIGS.7(b) to 9(b) in an overlapped manner;

FIG. 11 is a scattered light intensity characteristic diagram showing ascattered light intensity with the lapse of time;

FIG. 12 is a perspective view of an ophthalmic refractive powermeasuring apparatus (a contact lens optical characteristics measuringapparatus) according to a second embodiment of the present invention;

FIG. 13 is a left side view of FIG. 12;

FIG. 14 is a perspective view of a face fixing device shown in FIG. 12;

FIG. 15 is a perspective view with a contact lens measuring attachmentattached to a jaw rest shown in FIG. 14;

FIG. 16 is a partially sectional view of the attachment shown in FIG.15;

FIG. 17(a) is a sectional view taken on line A—A in FIG. 16;

FIG. 17(d) is an explanatory diagram showing a state of rotation of aring pattern beam on a surface of a soft contact lens;

FIG. 18 is an explanatory diagram of an optical system in the ophthalmicrefractive power measuring apparatus of the second embodiment;

FIG. 19 is an explanatory diagram showing a state of a pattern imageformed on the eyeground by the optical system shown in FIG. 18;

FIG. 20 is an explanatory diagram showing a relation between a patternimage formed on a light receiving element in the optical system shown inFIG. 18 and peak positions;

FIGS. 22(A) to (F) are explanatory diagrams each showing a relationbetween an arbitrarily stored example of the pattern image formed on theeyeground in FIG. 18 and peak positions corresponding to the patternimage;

FIG. 21 shows a modified example of a deflecting member, in which (A) isan explanatory diagram of a rotary prism in a non-deflected state oflight beam and (B) is an explanatory diagram of the rotary prism in adeflected state of light beam;

FIG. 23 is an explanatory diagram showing an example of contact lensmeasurement using the ophthalmic refractive power measuring apparatusshown in FIG. 18;

FIG. 24 is a side view of an apparatus for measuring a refractive powerof a contact lens according to a third embodiment of the presentinvention;

FIG. 25 is an explanatory diagram of an optical system used in therefractive power measuring apparatus of FIG. 24;

FIG. 26 is an explanatory diagram showing a construction according to afourth embodiment of the present invention;

FIG. 27 is a graph showing changes with time in optical characteristicsof a soft contact lens;

FIG. 28 is an explanatory diagram showing a construction according to afifth embodiment of the present invention;

FIG. 29 is an explanatory diagram showing a construction according to asixth embodiment of the present invention;

FIG. 30 is an explanatory diagram showing a construction according to aseventh embodiment of the present invention; and

FIG. 31 is an explanatory diagram showing a soft contact lens whoseimage is formed on a CCD.

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment]

A first embodiment of the present invention will be describedhereinunder with reference to the drawings.

[Construction]

In FIG. 1, reference numeral 1 denotes a measuring optical system of alens meter as an example of a refractive power measuring apparatusaccording to the first embodiment. The measuring optical system 1 has ameasuring light projecting optical system 2 and a light receivingoptical system 3, with a lens rest 4 being disposed between the opticalsystems 2 and 3.

The measuring light projecting optical system 2 has a measuring lightsource 5, a pinhole plate 6, and a collimator lens 7. The lightreceiving optical system 3 has a pattern plate (pattern light formingmeans) 8 and a photosensor 9 such as an area CCD. Four aperture patterns8 a are formed in the pattern plate 8, as shown in FIG. 2. The wholesurface of the photosensor 9 (light receiving means) as a lightreceiving element serves as a measuring signal receiving portion and ascattered light receiving portion. In FIG. 1, reference mark O denotes ameasuring optical axis of the measuring optical system.

An output signal (received light signal) from the photosensor 9 isinputted to an arithmetic and control circuit (arithmetic and controlmeans; calculation means) 10. More specifically, an output signal from acentral side of the photosensor 9 is fed as a measured signal to thearithmetic and control circuit 10, while an output signal from aperipheral portion of the photosensor 9 is fed as a measured scatteredlight signal to the arithmetic and control circuit.

“ON” signals provided from switches S1 and S2, which are for switchingfrom one measuring mode to another, are fed to the arithmetic andcontrol circuit 10. The switch S1 functions to set the lens meter to amode for measuring optical characteristic values in air of a softcontact lens. The switch S2 functions to set the lens meter to a modefor measuring a lens other than the soft contact lens, e.g., a hardcontact lens measuring mode or a glasses lens measuring mode.

A display unit (display means) 11 such as a monitor television or aliquid crystal display, as well as a memory M, are connected to thearithmetic and control circuit 10. The arithmetic and control Circuit 10determines S, C, A (wherein S is defined as spherical power, C isdefined as cylindrical power, and A is defined as cylindrical axis) of asoft contact lens TL repeatedly at every short time. The 5, C, and Athus determined are displayed on the display unit 11 and the values ofS, C, and A on the display unit 11 are updated at every measurement.

[Operation]

The function, as well as operation, of the arithmetic and controlcircuit 10 in the lens meter of such a construction will be describedbelow.

When a power supply (not shown) is turned ON, the arithmetic and controlcircuit 10 operates to turn ON the measuring light source 5 in themeasuring light projecting optical system 2. The measuring light(illuminating light) from the measuring light source 5 passes through apinhole 6 a formed in the pinhole plate 6 and then enters the collimatorlens 7, whereby it is made into a parallel measuring beam (parallelbeam). The parallel measuring beam is projected on the lens rest 4 side.

In the case where a lens to be inspected is not positioned on the lensrest 4, the four aperture patterns 8 a of the pattern plate 8 areprojected on the photosensor 9 directly as aperture pattern images 8 a′through the parallel measuring beam, as shown in FIG. 3. At this time, asignal provided from the photosensor 9 is fed to the arithmetic andcontrol circuit 10, which in turn stores coordinates of the aperturepattern images 8 a′ at this instant into the memory M as patternreference data for the calculation of optical characteristics.

When a lens to be inspected is positioned on the lens rest 4, a parallelmeasuring beam passes through the lens to be inspected and is refracted.Thereafter, with the thus-refracted measuring beam, the four aperturepatterns 8 a of the pattern plate 8 are enlarged or reduced andprojected as aperture pattern images onto the photosensor 9.

On the other hand, when the switch S1 is turned ON, the arithmetic andcontrol circuit 10 sets the lens meter to a mode for measuring opticalcharacteristic values in air of the soft contact lens. With the switchS2 turned ON, the arithmetic and control circuit 10 sets the lens meterto a mode for measuring a lens other than the soft contact lens, e.g., ahard contact lens measuring mode or a glasses lens measuring mode.

<Measuring the Soft Contact Lens>

Reference will here be made to the case where the soft contact lens isto he measured. A description will first be given about a surfacecondition of the soft contact lens TL.

(1) Change in Surface Condition of the Soft Contact Lens

When the soft contact lens TL is placed on the lens rest 4 and themeasurement of its optical characteristics is started, the soft contactlens TL, which 2 usually dipped in an isotonic sodium chloride solutionwithin a lens receptacle, is taken out from the lens receptacle and isplaced on the lens rest 4 as in FIG. 1. Just after the placing of thelens on the lens rest, a large amount of liquid 12 such as isotonicsodium chloride solution or water is deposited on the surface of thesoft contact lens TL, as shown in FIG. 4(a).

In the case where the measurement of the soft contact lens TL is startedupon the lapse of time and dying of the lens after placing of the lenson the lens rest 4, or when the measurement is started after placing adry soft contact lens TL on the lens rest 4, liquid 14 such as isotonicsodium chloride solution or water is added dropwise onto the softcontact lens TL from a dropping pipette (not shown), allowing a largeamount of the liquid 14 to be deposited on the surface of the softcontact lens TL, as shown in FIG. 4(a). This is because it is necessarythat a refraction characteristic of the soft contact lens TL be measuredunder the same condition as a working condition.

From the start of measurement the soft contact lens TL changessuccessively like (i) a large amount of liquid holding state, (ii) acompatibility state, and (iii) a dried state.

(i) Initial Stage of Measurement (a Large Amount of Liquid HoldingState)

When the measurement is started, the soft contact lens TL is wet into astate in which a large amount of liquid 14 is deposited on the lenssurface, as shown in FIG. 4(a). In this state, the liquid 14 adheres aswater drops in a concave-convex form onto the surface of the softcontact lens TL.

(ii) Intermediate Stage of Measurement (a Compatibility State)

During measurement, the liquid 14 deposited on the surface of the softcontact lens TL flows down along a curve of the lens surface, or aportion of the liquid 14 deposited on the lens surface evaporates or isabsorbed by the soft contact lens TL, so that the liquid 14 becomescompatible with the lens. In this compatibility state, the liquid on thelens surface assumes ε layer form of a uniform thickness as shown inFIG. 4(b), or the lens surface dries moderately into a smooth state.

(iii) Last stage of measurement (a dried state)

Further, as the absorption of water by the soft contact lens TLproceeds, resulting in the lens becoming dry, a surface 14 a and a back14 b of the lens are roughened as shown in FIG. 4(c).

(2) Measuring the Soft Contact Lens

For measuring optical characteristics of the soft contact lens, theswitch S1 is turned ON to set the lens meter into the mode for measuringoptical characteristic values in air of the lens.

Then, the soft contact lens TL is placed on the lens rest 4. In thisstate, the measuring light (illuminating light) from the measuring lightsource 5 passes through the pinhole 6 a of the pinhole plate 6 andenters the collimator lens 7, whereby it is made into a parallelmeasuring beam (parallel beam). The parallel measuring beam is projectedon the soft contact lens TL placed on the lens rest 4.

After the parallel measuring beam passes through the soft contact lensTL and is reacted, the four aperture patterns 8 a of the pattern plate 8are projected on the photosensor 9 by the refracted measuring beam.

At this time, if the surface of the soft contact lens TL is smooth, theparallel measuring beam is refracted with only the refractive power ofthe lens TL and projects the four aperture patterns 8 a onto thephotosensor 9. Besides, according to whether the soft contact lens TL isa convex lens or a concave lens, the four aperture patterns 8 a (theirspacing and aperture diameter) are projected in an enlarged or reducedstate onto the photosensor 9 and aperture pattern images 8 a′ of thethus-enlarged or—reduced four aperture patterns 8 a are formed on thecentral side of the photosensor 9, as shown in FIG. 6. Further, when thesoft contact lens TL has no cylindrical , the aperture pattern images 8a′ of the four aperture patterns 8 a are formed on a circle r centeredat a measuring optical axis O. On the other hand, when the soft contactlens TL has a cylindrical axis, the aperture pattern images 8 a′ of thefour aperture patterns 8 a are formed on an ellipse centered at themeasuring optical axis O, as shown in FIG. 6. The cylindrical axis isoriented in the major axis direction of the ellipse.

By obtaining an enlargement or reduction ratio of the aperture patternimages there are obtained optical characteristic values S, C, and A ofthe soft contact lens TL.

In measuring optical characteristics of the soft contact lens TL, thesoft contact lens is fully wet with liquid 14 and then placed on thelens rest 4, or the liquid 14 is added dropwise to the soft contact lensplaced on the lens rest 4 to wet the lens to a satisfactory extent. Thisis because it is necessary that a refraction characteristic of the softcontact lens TL be measured under the same condition as a workingcondition of the lens.

At the beginning of the measurement (initial stage of the measurement),however, the surface of the soft contact lens TL is uneven with a largeamount of liquid 14 as in FIG. 4(a). Consequently, a parallel measuringbeam incident on the soft contact lens TL at the beginning of themeasurement is refracted by both a refractive power of the uneven liquid14 deposited on the lens surface and a refractive power of the lens TL.Thus, the parallel measuring beam incident on the soft contact lens TLat the beginning of the measurement is refracted or scattered under theinfluence of the refractive power of the uneven liquid 14.

Consequently, the aperture pattern image of the four aperture patterns 8a, which are projected on the photosensor 9 with a measuring beam 15shown in FIG. 7(a), are formed at positions offset from the circle orellipse centered on the measuring optical axis O.

Besides, scattered light aperature images (not shown) of the aperturepatterns 8 a based on scattered light 16 are formed on the photosensor9, as shown in FIG. 7(a). At this time, an output (measured signal) Oa1based on the measuring beam 15, an output (measured scattered lightsignal) Ob1 based on the measuring beam 16, and a noise output Oc1 areobtained from the photosensor 9, as shown in FIG. 7(b). The noise outputOc1 is detected at about the same level throughout the whole of thephotosensor 9. Thus, while the outputs Ob1 and Oc1 are detected, opticalcharacteristics of the soft contact lens TL cannot be measuredaccurately.

As the measurement time elapses, the liquid 14 present on the surface ofthe soft contact lens TL becomes thin and compatible with the lenssurface, indicated at 14 a, as shown in FIGS. 4(b) and 8(a), whereuponthe output Ob1 from the photosensor 9 and the noise output Oc1 bothshown in FIG. 7(b) become zero and are no longer outputted as in FIG.8(b). At this time, the output Oa1 shown in FIG. 7(b) increases in thequantity of light correspondingly to the decrease (nearly zero) ofscattered light and becomes clear, affording such an output Oa2 as shownin FIG. 8(b).

In this case, optical characteristic values S, C, A of the soft contactlens TL become equal in a precise sense to the optical characteristicvalues S, C, A in air which the original shape of the lens TL possesses.Therefore, the arithmetic and control circuit 10 detects measuredsignals provided from the photosensor 9, and when the outputs Ob1 andOc1 have dropped below a predetermined value (below a preset value,i.e., nearly “0”) (time t1 in FIG. 11 to be described later), thearithmetic and control circuit stores calculated optical characteristicsS, C, and A into memory (not shown). The optical characteristics S, C, Athus stored in memory continue to be displayed on the display unit 11without being updated.

Calculation of the optical characteristic values S, C, A is performed inthe following manner. Coordinates of the outputs Oa2 (four outputscorresponding respectively to the four aperture patterns 8 a) are storedas measurement pattern data into memory M, the arithmetic and controlcircuit 10 determines an enlargement or reduction ratio and a change ofthe aperture pattern images on the photosensor 9 on the basis of themeasurement pattern data and reference pattern data and calculatesoptical characteristic values S, C, A of the soft contact lens TL.

Further, as the measurement time elapses, the surface and the back ofthe soft contact lens TL arc roughened, as shown in FIGS. 4(c) and 9(a).At this time, scattered light 16′ is projected substantially uniformlyon the photosensor 9, as shown in FIG. 9(a), so that the quantity oflight of the aperture patterns 8 a projected on the photosensor 9decreases and an output Oc2 based on the scattered light is obtained asnoise. Consequently, the outputs Oa2 in FIG. 8(b) decrease in theirquantity of light to a greater extent than the outputs Oa1 in FIG. 7(b),affording such outputs Oa3 as shown in FIG. 9(b). In this case, aperturepattern images of the aperture patterns 8 a projected on the photosensor9 through the soft contact lens TL are not obtained as clear images butare blurred, so that the optical characteristic values S, C, A obtainedare different from optical characteristic values S, C, A in air whichthe original shape of the soft contact lens TL possesses. Thus, also inthe case of FIG. 9 it is impossible to accurately measure the opticalcharacteristics of the soft contact lens TL.

If such outputs of the photosensor 9 as shown in FIGS. 7(b) to 9(b) areoverlap-displayed for comparison, the result is as shown in FIG. 10.

In the measurement of the soft contact lens TL, the scattered lightintensity varies as indicated with a scattered light intensity curve Bin FIG. 11. That is, at the beginning of the measurement, as shown inFIG. 7(a), the liquid 14 present on the surface of the soft contact lensTL is not uniform, so that the intensity of scattered light passingthrough the soft contact lens TL is high as at time “0” in FIG. 11.Since the liquid 14 on the lens surface becomes uniform gradually, theintensity of scattered light passing through the soft contact lens TLbecomes small to near “0” as in FIG. 11. At a latter stage of themeasurement after the time t2, as shown in FIG. 9(a), the surface of thesoft contact lens TL becomes dry and fine concaves and convexes areformed thereon, which become larger gradually. Consequently, theintensity of scattered light passing through the soft contact lens TLbecomes larger gradually, as shown in FIG. 11.

Thus, also from FIG. 11 it is seen that the optical characteristicvalues S, C, A of the soft contact lens TL can be obtained on the basisof the outputs Oa2 which are provided from the photosensor 9 during theperiod of time t1-t2.

The optical characteristic values S, C, A thus obtained are displayed onthe display unit 11.

Although in the above embodiment the light of scattered light apertureimages based on scattered light is detected by utilizing a part of thephotosensor 9, a photosensor (light receiving element) separate from thephotosensor 9 may be provided as a scattered light receiving portion.

(3) Others

In the method for measuring optical characteristics of a soft contactlens according to the present invention, as described above, the patternplate (pattern light forming means) 8 is disposed at a certain positionin the measuring optical path of the measuring optical system 1extending from the measuring light source 5 to the photosensor (lightreceiving element) 9, the measuring light from the light source 5 ismade into a pattern light by the pattern plate 8, which pattern light isallowed to be received by the photosensor 9, and when the soft contactlens TL is disposed at a certain position in the measuring optical path,a change of the pattern light received by the photosensor 9 isdetermined from a change of the measured signal outputted from thephotosensor 9, thereby obtaining optical characteristic values of thesoft contact lens TL disposed at a certain position in the measuringoptical path. Besides, the soft contact lens TL, which is in a wetstate, is in air and at a certain position in the measuring optical pathand scattered light developed upon scattering of the measuring lightafter passing through the soft contact lens TL is received by thephotosensor 9, whereupon measurement is started. Further, a state ofscatter of the scattered light is determined from a change of themeasured signal caused by a change of the pattern light which isreceived by the photosensor 9, and the optical characteristic values areobtained when the measured signal outputted from the photosensor 9 hasattenuated to below a preset value.

In this optical characteristics measuring method for the soft contactlens it is desirable that the soft contact lens TL be wet with liquidsuch as an isotonic sodium chloride solution or water at the time ofstarting the measurement.

The measurement comprises a first stage in which a large amount ofliquid is deposited on the surface of the soft contact lens TL, a mediumstage in which the liquid is absorbed by the soft contact lens TL orevaporates or flows down and the liquid on the lens surface forms auniform layer, and a last stage in which the absorption of water by thesoft contact lens TL and drying proceed and the lens surface becomesrough. By obtaining optical characteristics of the soft contact lens TLfrom the measuring signal in the above medium stage there can beobtained accurate results.

The apparatus for measuring optical characteristics of a soft contactlens according to the present invention comprises the measuring opticalsystem 1 in which the pattern plate (pattern light forming means) 8 isdisposed at a certain position in a measuring optical path extendingfrom the light source 5 to the photosensor (light receiving element) 9to make the measuring light omitted from the light source 5 into apattern light, allowing the pattern light to be received by thephotosensor 9, and the arithmetic and control circuit 10 which, when thesoft contact lens TL is disposed at a certain position in the measuringoptical path, determines a change of the pattern light received by thephoto sensor 9 on the basis of a change of a measured signal providedfrom the photosensor, thereby obtaining optical characteristic values ofthe soft contact lens TL disposed at a certain position in the measuringoptical path. The photosensor 9 is provided so that it can receivescattered light developed upon passage of the measuring light throughthe soft contact lens TL and output a measured scattered light signal.The arithmetic and control circuit 10 determines the opticalcharacteristic values from the measured signal when the measuredscattered light signal is blow a preset value after the start ofmeasurement with the soft contact lens TL placed on the lens rest 4 at acertain position in the measuring optical path.

As noted above, the scattered light receiving portion which receivesscattered light generated upon passage of the measuring light throughthe soft contact lens and which outputs a measured scattered lightsignal may be provided separately from the photosensor (light receivingelement) 9.

[Second Embodiment]

[Construction]

FIGS. 12 to 23 illustrate a second embodiment of the present invention.In this second embodiment, a face fixing device 200 is mounted to anophthalmic refractive power measuring apparatus 100 and an attachment300 for contact lens measurement, which is shown in FIGS. 15 to 17, isattached to the face fixing device 200, thereby permitting theophthalmic refractive power measuring apparatus 100 to make such ameasurement of the soft contact lens TL as described above.

In FIGS. 12 and 13, the numeral 101 denotes a fixed base of theophthalmic refractive power measuring apparatus 100, numeral 102 denotesa movable base which is mounted on the fixed base 101 so as to bemovable in both longitudinal and transverse directions, and numeral 103denotes a joy stick lever for moving the movable base 102 in bothlongitudinal and transverse directions. On the movable base 102 ismounted a case 104 which incorporated a three-dimensional drive unit(not shown), and on the case 104 is mounted an apparatus body 105 whichincorporates a refractive power measuring optical system. The refractivepower measuring optical system is adapted to be given inthree-dimensional directions by the three-dimensional drive unit (notshown) disposed within the case 104.

The three-dimensional drive unit 104 can be operated by both joy sticklever 103 and an arithmetic and control circuit (arithmetic and controlmeans) (not shown). For this construction there may be adopted a knownconstruction and therefore a detailed explanation thereof will here beomitted.

A TV monitor (display unit) 104 a is mounted on a back side of the case104.

<Face Fixing Device 200>

The face fixing device (face fixing means) 200 has a support member 201which is attached to a transversely central part of a front end side ofthe fixed base 101, as shown in FIGS. 14 and 15. The support member 201has L-shaped side faces and extends vertically, as shown in FIGS. 13 to15. A jaw support portion 202, which extends right and left, is integralwith an upper end of the support member 201.

The face fixing device 200 has a jaw rest support shaft 203 which isconnected to a jaw rest support portion 202 in a vertically movablemanner, a jaw rest 204 secured to an upper end of the jaw rest supportshaft 203, and a forehead pad support frame 206 which extends verticallyin an inverted U shape and both ends of which are secured onto both endsof the jaw rest support shaft 203.

The jaw rest support shaft 203 is positioned centrally in the transversedirection of the jaw rest support portion 202 and can be adjusted itsvertical movement by a drive means such as a drive motor (not shown).For this construction there may be adopted a known construction andtherefore an explanation thereof will here be omitted. The jaw rest 204comprises a recess 204 a for resting the jaw thereon (for jaw support)positioned centrally in the transverse direction and a pair ofhorizontal portions 204 b positioned right and left of the recess 204 a.Pin mounting holes 206 ere formed in the horizontal portions 204 brespectively, as shown in FIG. 16.

The face fixing device 200 is further provided with a pair of positionrestricting pins 207 thread engaged in the pin mounting holes 206 andprojecting upward and a forehead pad 208 attached to an upper end of theforehead pad support frame 205. The face fixing device 200 can also bemounted by press-fitting tho position restricting pins 207 into the pinmounting holes 206.

<Attachment 300 for contact lens measurement>

As shown in FIGS. 16 to 17, the attachment 300 has a part mounting plate301, a model eye 302, a lens rest 303, a mirror mounting plate 304, anda reflecting mirror 305.

The part mounting plate 301 comprises a horizontal, lower mounting plateportion 301 a, a plate portion 301 b which extends upward substantiallyvertically from a front edge of the lower mounting plate portion 301 a,and an upper mounting plate portion 301 c which extends horizontallybackward from an upper end of the plate portion 301 b. On the right andleft sides of the lower mounting plate portion 301 a are formed pininsertion holes 306 respectively at the same spacing as that of the pinmounting holes 206 of the jaw rest 204, as shown in FIG. 16.

As shown in FIGS. 16 and 17(a), the model eye 302 has a cylindrical body307 extending vertically and a reflecting mirror 308 disposed within alower end portion of the body 307. An upper end portion of the body 307is fixed with screws 309 to the underside of a transversely central partof the upper mounting plate portion 301 c. Moreover, a lens restmounting hole 310 concentric with the body 307 and larger in diameterthan the inside diameter of the body 307 is formed in the upper mountingplate portion 301 c. A lower end portion of the lens rest 303 is fittedin the lens rest mounting hole 310. The lens rest 303 may be fixed bybonding to the body 307 and the lens rest mounting hole 310. The lensrest 303 may be fixed by bonding or threadedly to the body 307 or thelens rest mounting hole 310.

Further, the mirror mounting plate 304 is fixed with screws 311 to anupper portion of the upper mounting plate portion 301 c in a 45°inclined state backward. The reflecting mirror 305 is fixed to a lowersurface of the mirror mounting plate 304 through a bracket 312 andscrews 313. A central part of the reflecting mirror 305 faces the lensrest 303.

By inserting the position restricting pins 207 into the pin insertionholes 306 of the attachment 300 having such a construction and bysubsequently bringing the pins 207 into threaded engagement in the pinmounting holes 206 of the jaw rest 204, the attachment 300 can bemounted to the jaw rest 204.

<Refractive Power Measuring Optical System>

Such a refractive power measuring optical system as shown in FIG. 18(A)is incorporated within the apparatus body 105. In FIG. 18(A), thenumeral 110 denotes a target projecting optical system which projects atarget on the eyeground Er to fix and fog the eye E to be inspected,numeral 120 denotes a viewing optical system for viewing a front eyeportion Ef of the eye E, numeral 180 denotes a scale projecting opticalsystem for projecting an aiming scale on a light receiving element S,numeral 140 denotes a pattern beam projecting optical system forprojecting a pattern beam on the eyeground Er which pattern beam is formeasuring a refractive power of the eye E, ad numeral 150 denotes alight receiving optical system which causes a light beam reflected fromthe eyeground Er to be received by the light receiving element S.

The target projecting optical system 110 comprises light source 111,collimator lens 112, target plate 113, relay lens 114, mirror 115, relaylens 116, dichroic mirrors 117 and 118, and objective lens 119.

Visible light emitted from the light source 111 is collimated into aparallel beam by the collimator lens 112 and then passes through thetarget plate 113. On the target plate 113 is provided a target forfiring and fogging the eye E. The target beam passes through the relaylens 114 and is reflected by the mirror 115, then passes through therelay lens 116 and is reflected by the dichroic mirror 117, then isconducted to a main optical axis O1 of the apparatus body, passesthrough the dichroic mirror 118 and is thereafter conducted to the eye Ethrough the objective lens 119.

The light source 111, collimator lens 112, and target plate 113 are heldby a lens barrel 110 a and unitized so as to be movable along an opticalaxis O2 of the target projecting optical system 110 to fix and fog theeye E. The lens barrel 110 a is moved forward and backward along theoptical axis O2 by means of a pulse motor PM1.

The viewing optical system 120 comprises light source 121, objectivelens 119, dichroic mirror 118, relay lens 122, diaphragm 123, mirror124, relay lens 125, dichroic mirror 126, imaging lens 127, and lightreceiving element S. In measuring a refractive characteristic of thesoft contact lens, the light receiving element S is also used as ascattered light receiving portion.

The light beam emitted from the light source 121 directly illuminatesthe front portion Ef of the eye E to be inspected. The light beamreflected by the front eye portion Ef passes through the objective lens119 and is reflected by the dichroic mirror 118, then passes through therelay lens 122 and at the same time passes through the diaphragm 123,then is reflected by the mirror 124, thereafter passes through the relaylens 125 and dichroic mirror 126, and is imaged on the light receivingelement S by the imaging lens 127.

The scale projecting optical system 130 comprises light source 131,collimator lens 132 provided with an aiming scale, relay lens 133,dichroic mirror 118, relay lens 122, diaphragm 123, mirror 124, relaylens 125, dichroic mirror 126, imaging lens 127, and light receivingelement S.

Light beam emitted from the light source 131 is made into an aimingscale beam (parallel beam) when passing through the collimator lens 132,then passes through the relay lens 133, dichroic mirror 118, relay lens122 and diaphragm 123 and is reflected by the mirror 124, further passesthrough the relay lens 125 and dichroic mirror 126 and is imaged on thelight receiving element S by the imaging lens 127.

For example, a two-dimensional area CCD is used as the light receivingelement S. A front eye portion image is conducted to a monitor (notshown) by means of the viewing optical system 120 and is displayedthereon. At the same time, an image based on the aiming scale isdisplayed on the monitor. The inspector performs operation for verticaland transverse alignment of both eye E and apparatus body so that thefront eye portion image displayed on the monitor approaches the aimingscale image. The inspector also performs operation for longitudinalalignment. In measuring a refractive power after the operation foralignment, the light sources 121 and 131 are turned OFF, or a shutter orthe like is provided in the optical path extending from the dichroicmirror 118 to the dichroic mirror 126 to inhibit the reception of lightin the light receiving element S.

The pattern beam projecting optical system 140 comprises light source141, collimator lens 142, conical prism 143, ring target plate 144,relay lens 145, mirror 146, relay lens 147, prism with hole 148, opticalaxis deflecting prism 149 as a deflector member, dichroic mirrors 117and 118, and objective lens 119. The light source 141 and the ringtarget plate 144 are optically conjugated with each other and the ringtarget plate 144 and a pupil Ep of the eye E are disposed opticallyconjugated positions.

Light beam emitted from the light source 141 is made into a parallelbeam by the collimator lens 142. The parallel beam passes through theconical prism 143 and is conducted to the ring target plate 144, thenpasses through a ring-like pattern portion formed on the ring targetplate 144 and becomes a pattern beam. The pattern beam passes throughthe relay lens 145, then is reflected by the mirror 146, passes throughthe relay lens 147 and is reflected along the main optical axis O1 bythe prism with hole 148, then passes through the dichroic mirrors 117and 118 while being obliquely deflected and offset from the main opticalaxis O1 by the optical axis deflecting prism 149, and is thereafterimaged on the eyeground Er by the objective lens 119.

The optical axis deflecting prism 149 is adapted to be rotated (seearrow) at high speed about the main optical axis O1 by means of thepulse motor PM2. With this high-speed rotation, the pattern beamprojected on the eyeground Er circles in an eccentric state about themain optical axis O1, as shown in FIG. 19.

The light receiving optical system 150 comprises objective lens 119,dichroic mirrors 118 and 117, optical axis deflecting prism 149, hole148 a of the prism with hole 148, relay lens 151, mirror 152, relay lens153, mirror 154, focusing lens 155, mirror 156, dichroic mirror 126,imaging lens 127, and light receiving element S.

The focusing lens 155 is movable along optical axes O3 and O4 of theoptical systems 140 and 150 together with the light source 141,collimator lens 142, conical prism 143 and ring target plate 144.

The light beam which has been conducted to the eyeground Er by thepattern beam projecting optical system 140 and reflected by theeyeground is condensed by the objective lens 119, then passes throughthe dichroic mirrors 118 and 117 and is conducted to the optical axisdeflecting prism 149. The light beam which has passed through theoptical axis deflecting prism 149 is conducted to the hole 148 a of theprism with hole 148 from the same portion centered on the main opticalaxis O1 in accordance with the principle of beam retogression and passesthrough the hole 148 a.

The reflected pattern beam having passed through the hole 148 a passesthrough the relay lens 151 and is reflected by the mirror 156, thenpasses through the relay lens 153 and is reflected by the mirror 154,further passes through the focusing lens 155 and is reflected by themirror 156 and the dichroic mirror 126, and a pattern image is formed onthe light receiving element S through the imaging lens 127.

The light receiving element S and the eyeground Er are conjugated witheach other and the ring target plate 144 is conjugated with theeyeground Er.

A video signal (received light signal; measured signal) provided fromthe light receiving element S is fed to an arithmetic and controlcircuit 160, as shown in FIG. 18(B). On the basis of the video signalprovided from the light receiving element S the arithmetic and controlcircuit (calculation means) 160 determines a refractive power of the eyeto be inspected and makes control to display the thus-determinedrefractive power on a TV monitor 149 a.

Moreover, the arithmetic and control circuit 160 controls the operationof the pulse motor PM1 to let the lens barrel 110 a move forward andbackward along the optical axis O2. Likewise, the arithmetic and controlcircuit 160 controls the operation of the pulse motor PM2 to let theprism 149 rotate at high speed around the optical axis O1. Besides, thearithmetic and control circuit 160 controls the lightning of the lightsources 111, 131 and, 141.

Further, the arithmetic and control circuit 160 makes control to letplural pattern images 144″ on the light receiving element S be stored ina storage medium 161 such as a frame memory.

[Operation]

The following description is now provided about measurement of the softcontact lens TL using the ophthalmic refractive power measuringapparatus 100 and attachment 300 both constructed as above.

(1) Measuring an Ophthalmic Refractive Power by the OphthalmicRefractive Power Measuring Apparatus 100

<Alignment>

Before starting the measurement, the light sources 111, 121 and 131 aretub ed ON by the arithmetic and control circuit 160 and the eye E to beinspected is fixed, further, an alignment operation is performed forboth eye E and apparatus body.

In this case, a visible light emitted from the light source 111 is madeinto a parallel beam by the collimator lens 112. The parallel beampasses through the target plate 113, forming a target beam of the targetplate 113. The target beam is projected on the eye E through the relaylens 114, mirror 115, relay lens 116, dichroic mirrors 117, 118 andobjective lens 119. The eye E is allowed to view the target light. Atthis time, the light source 111, collimator lens 112 and target plate113, which are unitized, are moved along the optical axis O2, allowingthe eye E-fixed target beam to be fogged to create a state in which theeye E views a remote point.

On the other hand, light beam emitted from the light source 121illuminates the front portion Ef of the eye E directly. Then, the lightbeam reflected by the front eye portion Ef passes through the objectivelens 119, dichroic mirror 118, relay lens 122, diaphragm 123, mirror124, relay lens 125, dichroic mirror 126, and is imaged on the lightreceiving element S by the imaging lens 127. Light beam emitted from thelight source 131 in the scale projecting optical system 130 is made intoan aiming scale beam (parallel beam) while passing through thecollimator lens 132. Thereafter, the aiming scale beam passes throughthe relay lens 133, dichroic mirror 118, relay lens 122 and diaphragm123 and is reflected by the mirror 124, then passes through the dichroicmirror 126 and is imaged on the light receiving element S by the imaginglens 127.

In this way a front eye portion image is conducted to the lightreceiving element S by the viewing optical system 120 and is formedthereon, and also formed thereon is an image based on the aiming scale.A video signal provided from the light receiving element S is fed to themonitor 104 a and a front eye portion image E′, as well as an imagebased on the aiming scale TS, are displayed on the monitor 104 a. Theinspector operates the joy stick lever 103 to effect alignment invertical and transverse directions for both eye E and apparats body 105so that the front eye portion image E′ displayed on the monitor 104 aapproaches the aiming scale image TS. The inspector also performs alongitudinal alignment operation for the front eye portion E′ displayedon the monitor 104 a.

<Measurement>

When the operation for alignment is over, the arithmetic and controlcircuit 160 turns OFF the light sources 121 and 131 so that the lightfrom the light sources 121 and 131 may not be projected on the lightreceiving element S. In this state, the arithmetic and control circuit160 turns ON the light source 141 in the pattern beam projecting opticalsystem 140.

Light beam emitted from the light source 141 in the pattern beamprojecting optical system is made into a parallel beam by the collimatorlens 142. Then, the parallel beam passes through the conical prism 143and is conducted to the ring target plate 144, then passes through aring-shaped pattern portion formed on the ring target plate 144 and isthereby made into a pattern beam. This pattern beam passes through therelay lens 145 and is thereafter reflected by the mirror 146, thenpasses through the relay lens 147 and is reflected along the mainoptical O1 by the prism with hole 148, further, passes through thedichroic mirrors 117 and 118 while being obliquely deflected and offsetfrom the main optical axis O1 by means of the optical axis deflectingprism 149, and is then imaged on the eyeground Er by the objective lens119.

In this case, the optical axis deflecting prism 149 is rotated (seearrow) at high speed about the main as O1 by the pulse motor PM2 whoseoperation is controlled by the arithmetic and control circuit 160. Withthis high-speed rotation, the pattern image projected on the eyegroundEr circles eccentrically around the main axis O1, as shown in FIG. 19.

The light beam which has been conducted to the eyeground Er by thepattern beam projecting optical system 140 and reflected by theeyeground is condensed by the objective lens 119, then passes throughthe dichroic mirrors 118 and 117 and is conducted to the optical axisdeflecting prism 149. The light beam which has passed through theoptical axis deflecting prism 149 is conducted to the hole 148 a of theprism with hole 148 from the same portion centered on the main opticalaxis O1 in accordance with the principle of beam retrogression andpasses through the hole 148 a.

The reflected pattern beam having passed through the hole 148 a passesthrough the relay lens 151 and is reflected by the mirror 152, thenpasses through the relay lens 153 and is reflected by the mirror 154,further passes through the focusing lens 155 and is reflected by themirror 156 and the dichroic mirror 126, and a pattern image is formed onthe light receiving element S by the imaging lens 127.

In this projection of pattern image 144′, if the inspector pushes ameasurement start switch (not shown), the arithmetic and control circuit160 makes control so that plural pattern images 144″ on the lightreceiving element S, which are based on pattern images 144′ formed atarbitrary positions of circumferences projected on the eyeground Er, arestored in the storage medium 161 such as a frame memory.

For example, as shown in FIGS. 21(A) to (F), if pattern images 144corresponding to pattern images 144′ offset at ring center O1′ from theoptical axis O1 are stored in the storage medium as patterns 144″ on thelight receiving element S, then in the states shown in FIGS. 21(A), D),(E) and (F), detected peak positions Q1 and Q2 are in agreement with anactual central position of image width, whereas in the states shown inFIGS. 21(B) and (C), peak positions Q3 and Q4 are offset from the actualcentral position of image width under the influence of a trouble 109.

If the peak positions Q1, Q3 and Q4 are averaged by the number of timesof storage, there can be calculated a peak position Q1′ which is closeto the actual central position of image width, as shown in the graph ofFIG. 20. Further, by calculating a center-to-center distance in theimage width in accordance with position information of the peakpositions Q1′ and Q2, it is possible to measure an ophthalmic refractivepower (the method for the measurement is known and is thereforeomitted). This calculation is performed by the arithmetic and controlcircuit 160.

<Others>

In the above second embodiment the optical axis deflecting prism 149 isused as a deflecting member, but for example as shown in FIG. 22(A), arotary prism 149′ having two prisms 149 a and 149 b capable of rotatingindependently and synchronously may be used as a deflecting member aid,for example as shown in FIG. 22(B), the whole of the rotary prism 149′may be rotated about the optical axis O1 while allowing one prism 149 bto rotate about the optical axis O1.

In this case, a deviation in output angle from the optical axis O1 canbe adjusted by adjusting independent rotations of the prisms 149 a and149 b, thus affording a wider application range than in the use of theoptical axis deflecting prism 149.

Thus, the range which can be influenced by the trouble 109 on thecircumferential track of each pattern image 144′ is very small ascompared with the range not influenced by the trouble 109. In the caseof the trouble 109 referred to as an example, such very small rangescorrespond to the ranges defined by the tracks shown in FIGS. 21(B) and(C), and the other ranges cab be said identical with normal eye ranges.Therefore, the larger the number of times the peak positions are storedin the storage medium, the higher the possibility of inputting eyegroundinformation on the portion not affected by the trouble 109. And byaveraging the results of measurement of center-to-center distances inthe width there can be obtained a measurement result which is highlyreliable to such an extent as permits ignoring a deviation caused by thetrouble 109.

The position of the trouble 109 on the eyeground Er differs depending onthe person to be inspected. Therefore, if the pattern image 144′ ismerely projected on a deviated position (deflected position), it islikely for a trouble 109 or the like to be present at the deviatedposition and there is a fear that the result of measurement may beerroneous. In the present invention, however, since the pattern image isrotated and storage is made plural times into the storage medium, thepossibility of inputting pattern images 144′ affected by the trouble 109decreases and it is possible to enhance the reliability of themeasurement result.

Although the pattern image 144′ is projected at a position deviated fromthe optical axis O1, the eye E to be inspected and the apparatus bodyare maintained in a predetermined certain relation by alignmentoperation, with no likelihood of impeding the reliability of measureddata.

Although in this embodiment the optical axis deflecting prism 149 isinserted in a shared portion of both pattern beam projecting opticalsystem 140 and light receiving optical system 150, no limitation is madethereto, but, for example, there may be adopted a construction whereinan optical axis deflecting prism of the same type is disposed in anunshared portion of each optical systems so that rotational angles ofboth such optical axis deflecting prisms are always equal to each other.With this construction, there can be obtained the same function andeffect as above.

(2) Measuring the Refraction of Soft Contact Lens TL

For measuring the refractive power of the soft contact lens TL with useof the ophthalmic refractive power measuring apparatus 100 constructedas above, the attachment 300 having the model eye 302 is attached to thejaw rest. In this case, first the position restricting pins 207 aremoved from the pin mounting holes 206 of the jaw rest 204 provided inthe face fixing device 200. Next, the position restricting pins 207 areinserted into the pin insertion holes 306 of the attachment 300 and arethen threadedly engaged in the pin mounting holes 206 of the jaw rest204.

In this way the attachment 300 is attached to the jaw rest 204, as shownin FIGS. 15 to 17. As a result, the model eye 302 is mounted on the jawrest 204 and the objective lens 119 faces the model eye 302 through thereflecting mirror 305 as in FIG. 23.

In this state the soft contact lens TL is put on the lens rest 204 ofthe attachment 300 as in FIGS. 16 and 17. Next, the light sources 121and 131 are turned ON through the arithmetic and control circuit 160 andan alignment operation for both apparatus body 105 and model eye 302 isperformed by operating the joy stick lever 103 in the same manner as thealignment operation for both apparatus body 105 and eye Er. In thiscase, it is not necessary to turn ON the light source 111.

When this alignment operation is over, the arithmetic and controlcircuit 160 turns OFF the light sources 121 and 131 so that the lightfrom both light sources may not be projected on the light receivingelement S. In this state the arithmetic and control circuit 160 turns ONthe light source 141 in the pattern beam projecting optical system 140.

The light beam emitted from the light source 141 in the pattern beamprojecting optical system 140 is made into a parallel beam by thecollimator lens 142. The parallel beam passes through the conical prism143 and is conducted to the ring target plate 144, then passes through aring-like pattern portion formed on the ring target plate 144 andbecomes a pattern beam.

The pattern beam passes through the relay lens 145, then is reflected bythe mirror 146, passes through the relay lens 147 and is reflected alongthe main optical axis O1 by the prism with hole 148, then passes throughthe dichroic mirrors 117 and 118 while being obliquely deflected anddeviated from the main optical axis O1 by the optical axis deflectingprism 149, then is projected on the surface of the soft contact lens TLthrough the objective lens 119 and reflecting mirror 305, passes throughthe soft contact lens TL and enters the body 307 of the model eye 302,then is projected and imaged on the reflecting mirror 308 disposedwithin the lower end portion of the body 307 and is reflected by themirror.

At this time the optical axis deflecting prism 149 is rotated (seearrow) at high speed about the man optical is O1 in the same manner asabove, and with this high-speed rotation, the pattern beam projected onboth soft contact lens TL and eyeground Er circles eccentrically aboutthe main optical axis O1, as shown in FIG. 19.

The pattern beam is conducted to the reflecting mirror 308 in the modeleye 302 by the pattern beam projecting optical system 140 and the beamreflected by the reflecting mirror 308 is condensed by the objectivelens 119 through the contact lens TL and reflecting mirror 305, thenpasses through the dichroic mirror 118 and 117 and is conducted to theoptical axis deflecting prism 149. The light beam which has passedthrough the optical axis deflecting prism 149 is conducted to the hole148 a of the prism with hole 148 from the same portion centered on themain optical axis O1 in accordance with the principle of beamretrogression and passes through the hole 148 a.

The reflected pattern beam having passed through the hole 148 a passesthrough the relay lens 151 and is reflected by the mirror 152, thenpasses through the relay lens 153 and is reflected by the mirror 154,further passes through the focusing lens 155 and is reflected by themirror 156 and the dichroic mirror 126, and a pattern image is formed onthe light receiving element S through the imaging lens 127.

As to the radius of gyration of the ring-like pattern beam on thesurface of the soft contact lens TL, it is convenient for themeasurement to set the said radius of gyration in such a manner that ifthe diameter of the soft contact lens TL is 8.8 mm and that of thering-like pattern beam is 2.5 mm, the diameter of gyration on thesurface of the soft contact lens TL is 3.5 mm, as shown in FIG. 17(b).

In the projection of the pattern image 144′, if the inspector pushes themeasurement start switch (not shown), the arithmetic and control circuit160 makes control so that plural pattern images 144″ on the lightreceiving element S, which are based on pattern images 144′ formed atarbitrary positions in the circumference projected on the reflectingmirror 308 in the model eye 302, are stored in a storage medium such asa frame memory.

Also in this case, as shown in FIG. 20, an ophthalmic refractive powercan be measured by calculating a center-to-center distance in the widthin accordance with positional information on peak positions Q1′ and Q2.

Also in this measurement using the ophthalmic refractive power measuringapparatus 100, the same measurements and calculations as in the (i)start of measurement (a large amount of liquid holding state), (ii)intermediate stage of measurement (a compatibility state) and (iii)latter stage of measurement (a dried state), which are conducted in thefirst embodiment, are carried out though the arithmetic and controlcircuit 160. In this way there can be attained a more accuratemeasurement.

According to this construction, even if the degree of wet of the softcontact leas TL is not uniform, it is possible to diminish the influencethereof and measure the optical characteristics S, C, A. Further, evenwhen the surface or the back of the soft contact lens TL is flawed orstained or even if the lens TL is distorted, the optical characteristicsS, C, A can be measured while diminishing the influence thereof.

In measuring the optical characteristic values of the soft contact lensTL, it is desirable that the optical axis deflecting prism 149 bedisposed at a position not conjugated with the back side (the side whichcontacts the cornea of the eye to be inspected) of the soft contactlens.

Although in the second embodiment it is the soft contact lens TL that ismeasured for optical characteristics, it is also possible to measureoptical characteristics of a hard contact lens. In this case, even ifthe hard contact lens is stained or flawed relatively heavily, it ispossible to measure optical characteristics thereof accurately withoutbeing influenced by such stain or flaw. In case of measuring opticalcharacteristics of a hard contact lens, it is not necessary to determineoptical characteristics in a time series manner.

[Third Embodiment]

Although the apparatus and method described in the above secondembodiment measures the refractive power of t the soft contact lens TLwith use of the ophthalmic refractive power measuring apparatus 100, alimitation is not always made thereto. For example, the refractive powermeasurement for the soft contact lens TL may be made using such adedicated lens refractive power measuring apparatus 400 as shown in FIG.24.

The lens refractive power measuring apparatus 400 has an apparatus body401 shown in FIG. 24. The apparatus body 401 comprises a base portion402, an upwardly extending support portion 403 which is integral with arear edge of the base portion 402, and a housing portion 404 positionedabove the base portion 402 and integral with an upper portion of thesupport portion 403. In the measuring optical system described in thesecond embodiment, both pattern beam projecting optical system 140 andlight receiving optical system 150 are incorporated within the housingportion 404. A lens barrel 405 which receives therein the objective lens119 used in the measuring optical system is projected downward from alower surface of the housing portion 404. On a front side of the housingportion 404 is mounted a TV monitor television 104 a.

Further, a model eye 302 is disposed below the lens barrel 405. Themodel eye 302 is mounted upward on the base portion 402 so that the axisthereof is aligned with the optical axis O1 of the objective lens 119. Alens rest 204 is attached to an upper end portion of the model eye 302.

In this construction, a soft contact lens TL is put on the lens rest 204as in FIGS. 24 and 26 and the light source 141 in the pattern beamprojecting optical system 140 is turned ON, whereby a refractive powerof the contact lens TL its measured in the same way as in the secondembodiment. Therefore, an explanation of this point will here beomitted. In FIG. 25, the light receiving element S and the reflectingmirror 308 are conjugated with each other and so are the ring targetplate 144 and the reflecting mirror 308.

According to this construction, even if the degree of wet of the softcontact lens TL is not uniform, it is possible to diminish the influencethereof and measure the optical characteristic values S, C, A. Besides,even when the soft contact lens TL is flawed or stained on its surfaceor back side or is distorted, the influence thereof can be diminished,permitting measurement of the characteristic values S, C, A.

In measuring the optical characteristic values of the soft contact lensTL, it is desirable that an optical axis deflecting prism 149 bedisposed at a position not conjugated with the back side (the sidecontacting the cornea of the eye to be inspected) of the soft contactlens.

Although in this third embodiment it is the soft contact lens TL that isto be measured for its optical characteristic values, it is alsopossible to measure optical characteristics of a hard contact lens. Inthis case, even if the hard contact lens is stained or flawed relativelyheavily, it is possible to measure optical characteristics thereofaccurately without being influenced by such stain or flaw. In this caseit is not necessary to determine optical characteristics of a hardcontact lens in a time series manner.

[Fourth Embodiment]

FIG. 26 illustrates a construction of a fourth embodiment of the presentinvention. A lens meter (a refractive power measuring apparatus) 500shown in FIG. 26 comprises a measuring optical system 501 which projectsa measuring light as a parallel beam onto a soft contact lens TL set ona lens rest 505, a light receiving optical system 510 which receives themeasuring light having passed through the soft contact lens TL, and aprocessor 520 which determines optical characteristics of the softcontact lens TL by an arithmetic processing.

The measuring optical system 501 comprises a light source 502constituted by an LED, a pinhole plate 503 having a pinhole 503 a, and acollimator lens 504 for collimating a light beam which has passedthrough the pin hole 503 a into a parallel beam.

The light receiving optical system 510 comprises a pattern plate 511 anda photosensor (light receiving means) 512 constituted by a CCD forexample. In the pattern plate 611 are formed four aperture patterns 511a at equal intervals centered on an optical axis. Pattern images basedon the measuring light having passed through the aperture patterns 511 aare formed on the photosensor 512.

The processor 520 comprises a calculation circuit 621 which calculatesoptical characteristics S, C, A of the soft contact lens TL at everypredetermined time in accordance with a received light signal providedfrom the photosensor 512, a memory (storage means) 522 which stores S,C, A calculated by the calculation circuit 521, a decision circuit 523which determines correct optical characteristics of the soft contactlens TL from a time series of S, C, A stored in the memory 522, and adisplay 524 which displays the correct optical characteristicsdetermined by the decision circuit 523.

Next, a description will be given below about the operation of the lensmeter according to this embodiment.

First, the soft contact lens TL, which is dipped in a preservationliquid, is taken out from a container (not shown) and is set onto thelens rest 505. Then, a main switch (not shown) is turned ON to turn ON ameasurement start switch (not shown). As a result, the light source 502goes ON and a measuring light is emitted from the lit source 502. Themeasuring light thus emitted passes through the pinhole 503 a of thepinhole plate 503 and reaches the collimator lens 504, whereby it ismade into a parallel beam. The parallel beam is projected on the softcontact lens TL.

The measuring light which has passed through the soft contact lens TLfurther passes through the aperture patterns 511 a formed in the patternplate 511 and reaches the photosensor 512. As a result, pattern imagesbased on the aperture patterns 511 a of the pattern plate 511 are formedon a light receiving surface 512A of the photosensor 512.

When the soft contact lens TL is not set on the lens rest 505, the samepattern images as the aperture patterns 511 a are formed on the lightreceiving surface 512A of the photosensor 512. In the case where thesoft contact lens TL is a concave lens, magnified pattern images areprojected on the light receiving surface 612A of the photosensor 512,while in case of the soft contact lens TL being a convex lens, reducedpattern images are formed on the light receiving surface 512A of thephotosensor 512. The photosensor 512 outputs received light signalscorresponding to the pattern images formed on the light receivingsurface 512A, while the calculation circuit 521 calculates S, C, A ofthe soft contact lens TL on the basis of the received light signalprovided from the photosensor 512. Since the method for this calculationis well known, a detailed explanation thereof will here be omitted.

On the basis of received light signals outputted from the photosensor512 the calculation circuit 521 calculates S, C, A of the soft contactlens TL at every predetermined time and stores the S, C, A values thusobtained into the memory 522.

As shown in FIG. 27, S, C, A are stored in time series into the memory522.

Water drops are deposited on the surface of the soft contact lens TLwhich has been taken out from the preservation liquid. The water dropsare thick and not uniform in thickness, but are wavy, on the surface ofthe soft contact lens TL. Consequently, S, C, A values measured at theinitial stage with the lens set on the lens rest 505 are largelydeviated from A are differentiated and the absolute values of thedifferential (|S/Δt|, |C/Δt|, |A/Δt|) are below predetermined values andif this state continues for a predetermined time or longer, this periodis judged to be the period T1 and the S, C, A values in this period aredisplayed. Alternatively, a time point t1 at which differential values(rate of change) of changes with time of S, C, A are minimum and a timepoint t2 at which differential values of changes with time of S, C, Abegin to increase, are determined and the period between the time pointst1 and t2 is judged to be the period T1.

Thus, by merely placing the wet soft contact lens TL on the lens rest505 it is possible to accurately mere correct optical characteristics ofthe soft contact lens TL, so that even a beginner can measure correctoptical characteristics of the soft contact lens TL without requiringskill which is required in the prior art.

Although in this fourth embodiment the S, C, A values in the period T1are displayed on the display 524, the S, C, A values stored in timeseries in memory 522 may be displayed together with the said display, asshown in FIG. 27.

Although in this fourth embodiment optical characteristics of the softcontact lens TL are measured by the lens meter 500, there may be adopteda method wherein S, C, A values are obtained in time series by theophthalmic refractive power measuring apparatus 100 described in thesecond embodiment or the lens refractive power measuring apparatus 400described in the third embodiment and correct S, C, A values areobtained in the same manner as above from the S, C, A values thusobtained in time series.

[Fifth Embodiment]

FIG. 28 illustrates a fifth embodiment of the present invention, inwhich the surface of a soft contact lens TL is photographed with a CCDcamera 600 and is displayed on the display 11.

In FIG. 28, the numeral 601 denotes a half mirror and numeral 602denotes an imaging lens. A CCD 603 of the CCD camera 600 and the surfaceof the soft contact lens TL are at conjugate positions with respect tothe imaging lens 602. In this fifth embodiment, a portion of themeasuring light beam emitted from the light source 5 is scattered at thesurface of the soft contact lens TL and the scattered light is receivedby the CCD camera 600.

In this fifth embodiment, the surface of the soft contact lens TLdisplayed on the display 11 is observed and the inspector judges whetherthe thickness of liquid 14 (see FIG. 4) on the lens surface has becomeuniform. When the answer is affirmative, S, C, A values of the softcontact lens are measured.

There may be adopted a construction wherein an image processing circuit605 is provided, as indicated with a broken line, and an image signal onthe surface of the soft contact lens TL, which is outputted from the CCD603, is subjected to an image processing in the image processing circuit605 to judge that the thickness of the liquid 14 on the lens surface hasbecome uniform. For example, when a luminance value of the image signalhas become uniform, it is judged that the thickness of the liquid 14 onthe lens surface has become uniform.

In this case, the arithmetic and control circuit 10 measures S, C, Avalues of the soft contact lens TL repeatedly at every short time, thenmakes control so that the measured S, C, A values are displayed on thedisplay 11, and updates the S, C, A values displayed on the display 11at every measurement. When the image processing circuit 605 judges thatthe thickness of the liquid 14 on the surface of the soft contact lensTL has become uniform, the display of the S, C, A values at this instantis locked. That is, S, C, A values of the soft contact lens TL obtainedupon arrival at a uniform thickness of the liquid 14 are displayed onthe display 11.

According to another method employable for judging a uniform thicknessof the liquid 14, a luminance value of each picture element, or pixel,of the CCD 603 is determined, and when the total number of pictureelements whose luminance values fall under a preset range, for examplewhen the said total number has reached 50 percent, it is judged that thethickness of the liquid 14 on the surface of the soft contact lens TLhas become uniform.

Although in this fifth embodiment the measuring light beam emitted fromthe light source 5 is scattered on the surface of the soft contact lensTL and this scattered light is received by the CCD 603 in the CCD camera600, there may be adopted a modification wherein another light source isprovided and a light beam emitted from this light source is radiated tothe surface of the soft contact lens TL, then scattered light resultingfrom scatter on the lens surface is received by the CCD camera 600.

[Sixth Embodiment]

FIG. 29 illustrates a sixth embodiment of the present invention. In thissixth embodiment, reflected light (scattered light) reflected by thesurface of the soft contact lens TL is received by a light receivingelement 610, and on the basis of the amount of light received by thelight receiving element 610 it is judged whether the thickness of theliquid 14 on the surface of the soft contact lens TL has become uniformor not. When the liquid thickness on the lens surface is judged to beuniform, S, C, A values of the soft contact lens TL at this instant aredisplayed on the display 11.

Also in this case, as is the case with the fifth embodiment, S, C, Avalues of the soft contact lens TL are measured repeatedly at everyshort time, the measured S, C, A values are displayed on the display 11,and the S, C, A values displayed on the display 11 are updated at everymeasurement. Then, the instant the thickness of the liquid 14 becameuniform, the display of S, C, A values is locked.

The judgment as to whether the thickness of the liquid 14 has becomeuniform or not is made by the arithmetic and control circuit 10. In thissixth embodiment, the instant the amount of light received by the lightreceiving element 610 became maximum, it is judged that the thickness ofthe liquid 14 has become uniform. The light source 5 and the lightreceiving element 610 are conjugated with each other. The lightreceiving element 610 may be a CCD.

Although in this sixth embodiment the measuring light beam emitted fromthe light source 5 is scattered on the surface of the soft contact lensTL and this scattered light is received by the light receiving element610, there may be adopted a modification wherein another light source isprovided and a light beam emitted from this light source is radiated tothe surface of the soft contact lens TL, then scattered light on thelens surface is received by the light receiving element 610.

[Seventh Embodiment]

FIG. 30 illustrates a seventh embodiment of the present invention. Inthis seventh embodiment, an illuminating optical system 700 and a lightreceiving optical system 710 are disposed sideways of the soft contactlens TL in order to judge whether the thickness of liquid 14 on the lenssurface has become uniform or not.

The illumination optical system 700 comprises a light source 701, apinhole plate 702, and a collimator lens 703.

The light receiving optical system 710 comprises an imaging lens 711 anda CCD 712. The CCD 712 and a central sectional position of the softcontact lens TL are conjugated with each other. As shown in FIG. 31, acentral sectional image of the soft contact lens TL is formed on the CCD712. That is, focusing is made to the central sectional position of thesoft contact lens TL.

An image signal outputted from the CCD 712 is fed to an image processingcircuit 720, which in turn performs an image processing for the imagesignal and judges whether the thickness of the liquid 14 on the softcontact lens TL has become uniform or not. Then, in the same way as inthe fifth embodiment S, C, A values of the soft contact lens TL aremeasured repeatedly at every short time and are displayed on the display11. Every time the measurement is made the S, C, A values on the display11 are updated.

Once the image processing circuit 720 judges that the thickness of theliquid 14 on the surface of the soft contact lens TL has become uniform,the display of S, C, A values at this instant is locked and displayed onthe display 11.

Effect of the Invention

Since the present invention is constructed as above, opticalcharacteristic values of a soft contact lens can be measured in airprecisely.

1. A refractive power measuring method for obtaining opticalcharacteristic values of a soft contact lens, wherein: when said softcontact lens which is in a wet state is disposed in air and at a certainposition in a measuring optical path of a measuring light, lightscattered from said soft contact lens is received by a light receivingelement, then a state of scatter of said scattered light is detectedfrom a change of a received light signal outputted from said lightreceiving element, and said optical characteristic values are determinedwhen the received light signal satisfies a predetermined condition.
 2. Arefractive power measuring method as claimed in claim 1, wherein: saidlight receiving element for receiving the scattered light is a lightreceiving element for the measurement of a refractive power; and saidsoft contact lens in a wet state is disposed in air and at a certainposition in said measuring optical path, scattered light resulting fromscatter of said measuring light when passing through said soft contactlens is received by said light receiving element, a state of scatter ofsaid scattered light is determined from a change of said received lightsignal caused by a change of said scattered light which is received bysaid light receiving element, and said optical characteristic values aredetermined when the received light signal outputted from said lightreceiving element satisfies the predetermined condition.
 3. A refractivepower measuring method as claimed in claim 1, wherein: said lightreceiving element for receiving the scattered light is a second lightreceiving element for receiving a surface-reflected light, said lightreceiving element being provided separately from a light receivingelement for the measurement of a refractive power; and a state ofscatter of scattered light resulting from projection of said measuringlight on said soft contact lens and reflection thereof on a surface ofthe soft contact lens in a wet state being disposed in air and at acertain position in said measuring optical path, is received by saidsecond light receiving element and is determined from a change of thereceived light signal outputted from said second light receivingelement, and when the received light signal outputted from the secondlight receiving element satisfies the predetermined condition, saidoptical characteristic values are determined on the basis of a receivedlight signal outputted from said light receiving element for themeasurement of a refractive power.
 4. A refractive power measuringmethod as claimed in claim 1, wherein said light receiving element is aCCD camera for receiving said scattered light, said CCD camera beingprovided separately from a light receiving element for the measurementof a refractive power, and when image data obtained by performing animage processing for an image signal outputted from said CCD camera issubstantially coincident with image data which has been obtainedbeforehand, in a smooth surface condition of the soft contact lens, itis judged that a state of scatter of a surface-reflected light of saidsoft contact lens satisfies the predetermined condition, then saidoptical characteristic values are determined on the basis of a receivedlight signal outputted from the light receiving element for themeasurement of a refractive power.
 5. A refractive power measuringmethod as claimed in claim 1, wherein at the beginning of measurement ofsaid soft contact lens, the soft contact lens is wet with an isotonicsodium chloride solution.
 6. A refractive power measuring method asclaimed in claim 1, wherein the measurement is made through an initialstage in which a large amount of liquid is deposited on a surface ofsaid soft contact lens, an intermediate stage in which said liquid isabsorbed by said soft contact lens or evaporates or flows down into auniform layer, and a last stage in which the absorption of water by thesoft contact lens and drying thereof proceed and the surface of the softcontact lens becomes rough, and said optical characteristic values ofthe soft contact lens are determined from said received light signal insaid intermediate stage of measurement.
 7. A refractive power measuringmethod as claimed in claim 1, wherein said scattered light is made intoa pattern light, and said pattern light is received by said lightreceiving element; and when a soft contact lens is disposed at a certainposition in said measuring optical path, a change of said pattern lightreceived by said light receiving element is determined from a change ofsaid received light signal outputted from the light receiving element,and thereby optical characteristic values of said soft contact lensdisposed at the certain position in said measuring optical path aredetermined.
 8. A refractive power measuring method as claimed in claim1, wherein optical characteristics of said soft contact lens arecalculated at every predetermined time in accordance with the outputsignal provided from said light receiving element, and correct opticalcharacteristics of the liquid-wet soft contact lens are determined froma time series of the calculated optical characteristics.
 9. A refractivepower measuring method as claimed in claim 8, wherein the calculatedoptical characteristics are stored in time series; and correct opticalcharacteristics of the liquid-wet soft contact lens are determined fromthe optical characteristics stored in time series.
 10. A refractivepower measuring apparatus for obtaining optical characteristic values ofa soft contact lens, comprising: a measuring optical system whichprojects a measuring light on said soft contact lens; a light receivingelement which receives a pattern light and scattered light from saidsoft contact lens when the soft contact lens in a wet state is disposedin air and at a certain position in a measuring optical path of ameasuring light; and a calculation means for calculating said opticalcharacteristic values when the received light signal outputted from saidlight receiving element satisfies a predetermined condition.
 11. Arefractive power measuring apparatus as claimed in claim 10, wherein:said light receiving element is a light receiving element for themeasurement of a refractive power; and said calculation means causessaid light receiving element to receive the scattered light of saidmeasuring light passed through said soft contact lens which is in a wetstate and is disposed in air and at a certain position in said measuringoptical path, thereby causing the measurement to be started, anddetermines a state of scatter of said scattered light from a change ofthe received light signal caused by a change of said scattered lightwhich is received by the light receiving element, then when the receivedlight signal satisfies the predetermined condition, the calculationmeans calculates said optical characteristic values of the soft contactlens.
 12. A refractive power measuring apparatus as claimed in claim 11,wherein: said measuring optical system has a pattern light projectingoptical system for projecting the pattern light onto a reflectingsurface through said soft contact lens; said light receiving element isprovided in a light receiving optical system, said light receivingoptical system being for conducting the pattern light to the lightreceiving element after the pattern light has been reflected by saidreflecting surface and returned through said soft contact lens; and saidpattern light projecting optical system and said light receiving opticalsystem share a part of respective optical portions, and a deflectingmember for deflecting and projecting the pattern light with respect toan optical axis of said pattern light projecting optical system isprovided in said shared portion.
 13. A refractive power measuringapparatus as claimed in claim 12, wherein said deflecting member is adeflecting prism which is rotated about the optical axis of said patternlight projecting optical system.
 14. A refractive power measuringapparatus as claimed in claim 12, wherein said deflecting member isdisposed at a position not conjugated with the disposed position of saidsoft contact lens in measuring optical characteristics of the softcontact lens.
 15. A refractive power measuring apparatus as claimed inclaim 10, wherein: said light receiving element is a second lightreceiving element for receiving a surface-reflected light, said secondlight receiving element being provided separately from a light receivingelement for the measurement of a refractive power, and said calculationmeans causes a state of scatter of scattered light to be received bysaid second light receiving element and determines it from a change ofthe received light signal outputted from said second light receivingelement, said scattered light resulting from projection of saidmeasuring light on said soft contact lens and reflection thereof on asurface of the soft contact lens, the soft contact lens being disposedin a wet state in air and at a certain position in said measuringoptical path, and when the received light signal outputted from saidsecond light receiving element satisfies the predetermined condition,said calculation means determines said optical characteristic values onthe basis of a received light signal outputted from said light receivingelement for the measurement of a refractive power.
 16. A refractivepower measuring apparatus as claimed in claim 15, wherein: saidmeasuring optical system has a pattern light projecting optical systemfor projecting the pattern light onto a reflecting surface through saidsoft contact lens; said light receiving element is provided in a lightreceiving optical system, said light receiving optical system being forconducting the pattern light to the light receiving element after thepattern light has been reflected by said reflecting surface and returnedthrough said soft contact lens; and said pattern light projectingoptical system and said light receiving optical system share a part ofrespective optical portions, and a deflecting member for deflecting andprojecting the pattern light with respect to an optical axis of saidpattern light projecting optical system is provided in said sharedportion.
 17. A refractive power measuring apparatus as claimed in claim16, wherein said deflecting member is a deflecting prism which isrotated about the optical axis of said pattern light projecting opticalsystem.
 18. A refractive power measuring apparatus as claimed in claim10, wherein: said light receiving element is a CCD camera providedseparately from a light receiving element for the measurement of arefractive power; and when image data obtained by performing an imageprocessing for an image signal outputted from said CCD camera issubstantially coincident with image data which has been obtainedbeforehand in a smooth surface condition of the soft contact lens, saidcalculation means judges that a state of scatter of a surface-reflectedlight of said soft contact lens satisfies the predetermined condition,and determines said optical characteristic values on the basis of areceived light signal outputted from the light receiving element for themeasurement of a refractive power.
 19. A refractive power measuringapparatus as claimed in claim 18, wherein: said measuring optical systemhas a pattern light projecting optical system for projecting the patternlight onto a reflecting surface through said soft contact lens; saidlight receiving element is provided in a light receiving optical system,said light receiving optical system being for conducting the patternlight to the light receiving element after the pattern light has beenreflected by said reflecting surface and returned through said softcontact lens; and said pattern light projecting optical system and saidlight receiving optical system share a part of respective opticalportions, and a deflecting member for deflecting and projecting thepattern light with respect to an optical axis of said pattern lightprojecting optical system is provided in said shared portion.
 20. Arefractive power measuring apparatus as claimed in claim 19, whereinsaid deflecting member is a deflecting prism which is rotated about theoptical axis of said pattern light projecting optical system.
 21. Arefractive power measuring apparatus as claimed in claim 10, wherein themeasurement is made through an initial stage in which a large amount ofliquid is deposited on a surface of said contact lens, an intermediatestage in which said liquid is absorbed by said soft contact lens orevaporates or flows down into a uniform layer, and a last stage in whichthe absorption of water by the soft contact lens and drying thereofproceed and the surface of the soft contact lens becomes rough, and saidcalculation means determines said optical characteristic values of thesoft contact lens from said received light signal in said intermediatestage of measurement.
 22. A refractive power measuring apparatus asclaimed in claim 21, wherein: said measuring optical system has apattern light projecting optical system for projecting the pattern lightonto a reflecting surface through said soft contact lens; said lightreceiving element is provided in a light receiving optical system, saidlight receiving optical system being for conducting the pattern light tothe light receiving element after the pattern light has been reflectedby said reflecting surface and returned through said soft contact lens;and said pattern light projecting optical system and said lightreceiving optical system share a part of respective optical portions,and a deflecting member for deflecting and projecting the pattern lightwith respect to an optical axis of said pattern light projecting opticalsystem is provided in said shared portion.
 23. A refractive powermeasuring apparatus as claimed in claim 22, wherein said deflectingmember is a deflecting prism which is rotated about the optical axis ofsaid pattern light projecting optical system.
 24. A refractive powermeasuring apparatus as claimed in claim 10, further comprising: apattern light forming means disposed at a certain position in ameasuring optical path extending from a light source to said lightreceiving element, a measuring light emitted from said measuring opticalsystem being made into a pattern light, and said pattern light beingreceived by said light receiving element; wherein said calculation meanscomprises an arithmetic and control circuit which, when said softcontact lens is disposed at a certain position in said measuring opticalpath, determines a change of the pattern light received by said lightreceiving element from a change of the received light signal outputtedfrom the light receiving element and thereby determines opticalcharacteristic values of said soft contact lens disposed at a certainposition in said measuring optical path, said light receiving elementcomprises a light receiving element portion which receives said patternlight and a scattered light receiving portion which receives scatteredlight resulting from passage of said measuring light through said softcontact lens and which outputs a received scattered light signal, andsaid calculation means determines said optical characteristic valuesfrom said received light signal when said received scattered lightsignal is below a preset value from the time when said soft contact lensis set in a wet state and measurement is started.
 25. A refractive powermeasuring apparatus as claimed in claim 24, wherein: said measuringoptical system has a pattern light projecting optical system forprojecting the pattern light onto a reflecting surface through said softcontact lens; said light receiving element is provided in a lightreceiving optical system, said light receiving optical system being forconducting the pattern light to the light receiving element after thepattern light has been reflected by said reflecting surface and returnedthrough said soft contact lens; and said pattern light projectingoptical system and said light receiving optical system share a part ofrespective optical portions, and a deflecting member for deflecting andprojecting the pattern light with respect to an optical axis of saidpattern light projecting optical system is provided in said sharedportion.
 26. A refractive power measuring apparatus as claimed in claim25, wherein said deflecting member is a deflecting prism which isrotated about the optical axis of said pattern light projecting opticalsystem.
 27. A refractive power measuring apparatus as claimed in claim10, further comprising: a decision means, wherein said calculation meanscalculates said optical characteristic values of said soft contact lensin a wet state at every predetermined time in accordance with an outputsignal provided from said light receiving means; and said decision meansdetermines correct optical characteristics of the wet soft contact lensfrom a time series of optical characteristic values calculated by saidcalculation means.
 28. A refractive power measuring apparatus as claimedin claim 27, wherein: said measuring optical system is a pattern lightprojecting optical system for projecting a pattern light onto areflecting surface through said soft contact lens, said pattern lightbeing for measuring a refractive power of the soft contact lens; saidlight receiving optical system is for conducting the pattern light tosaid light receiving means after the pattern light has been reflected bysaid reflecting surface and returned through said soft contact lens; andsaid pattern light projecting optical system and said light receivingoptical system share a part of respective optical portions and adeflecting member for deflecting and projecting the pattern light withrespect to an optical axis of said pattern light projecting opticalsystem is provided in said shared portion.
 29. A refractive powermeasuring apparatus as claimed in claim 28, wherein said deflectingmember is a deflecting prism which is rotated about the optical axis ofsaid pattern light projecting optical system.
 30. A refractive powermeasuring apparatus as claimed in claim 29, wherein said deflectingmember is disposed at a position not conjugated with the disposedposition of said soft contact lens in measuring optical characteristicsof the soft contact lens.
 31. A refractive power measuring apparatus asclaimed in claim 28, wherein said deflecting member is disposed at aposition not conjugated with the disposed position of said soft contactlens in measuring optical characteristics of the soft contact lens. 32.A refractive power measuring apparatus as claimed in claim 10, furthercomprising: a storage means, and a decision means, wherein a saidcalculation means calculates said optical characteristic values of saidsoft contact lens in a wet state at every predetermined time inaccordance with an output signal provided from said light receivingmeans; said storage means stores in time series the opticalcharacteristic values calculated by said calculation means; and saiddecision means determines correct optical characteristic values of thewet soft contact lens from the optical characteristics stored in timeseries in said storage means.
 33. A refractive power measuring apparatusas claimed in claim 32, wherein said decision means determines a periodof less variation in the optical characteristics from the opticalcharacteristics stored in time series in said storage means, anddetermines the optical characteristics in said period to be correctoptical characteristics of said soft contact lens.
 34. A refractivepower measuring apparatus as claimed in claim 33, wherein: saidmeasuring optical system is a pattern light projecting optical systemfor projecting a pattern light onto a reflecting surface through saidsoft contact lens, said pattern light being for measuring a refractivepower of the soft contact lens; said light receiving optical system isfor conducting the pattern light to said light receiving means after thepattern light has been reflected by said reflecting surface and returnedthrough said soft contact lens; and said pattern light projectingoptical system and said light receiving optical system share a part ofrespective optical portions and a deflecting member for deflecting andprojecting the pattern light with respect to an optical axis of saidpattern light projecting optical system is provided in said sharedportion.
 35. A refractive power measuring apparatus as claimed in claim32, wherein said decision means determines a period in which a variationin the optical characteristics is kept below a predetermined value overa certain time or longer, on the basis of the optical characteristicsstored in time series in said storage means, and determines the opticalcharacteristics in said period to be correct optical characteristics ofsaid soft contact lens.
 36. A refractive power measuring apparatus asclaimed in claim 35, wherein: said measuring optical system is a patternlight projecting optical system for projecting a pattern light onto areflecting surface through said soft contact lens, said pattern lightbeing for measuring a refractive power of the soft contact lens; saidlight receiving optical system is for conducting the pattern light tosaid light receiving means after the pattern light has been reflected bysaid reflecting surface and returned through said soft contact lens; andsaid pattern light projecting optical system and said light receivingoptical system share a part of respective optical portions and adeflecting member for deflecting and projecting the pattern light withrespect to an optical axis of said pattern light projecting opticalsystem is provided in said shared portion.
 37. A refractive powermeasuring apparatus as claimed in claim 32, wherein said decision meansregards the optical characteristics in a period from the time when therate of a change with time of the optical characteristics is minimumuntil the time when said rate of change begins to increase as correctoptical characteristics of said soft contact lens.
 38. A refractivepower measuring apparatus as claimed in claim 37, wherein: saidmeasuring optical system is a pattern light projecting optical systemfor projecting a pattern light onto a reflecting surface through saidsoft contact lens, said pattern light being for measuring a refractivepower of the soft contact lens; said light receiving optical system isfor conducting the pattern light to said light receiving means after thepattern light has been reflected by said reflecting surface and returnedthrough said soft contact lens; and said pattern light projectingoptical system and said light receiving optical system share a part ofrespective optical portions and a deflecting member for deflecting andprojecting the pattern light with respect to an optical axis of saidpattern light projecting optical system is provided in said sharedportion.
 39. A refractive power measuring apparatus as claimed in claim32, wherein: said measuring optical system is a pattern light projectingoptical system for projecting a pattern light onto a reflecting surfacethrough said soft contact lens, said pattern light being for measuring arefractive power of the soft contact lens; said light receiving opticalsystem is for conducting the pattern light to said light receiving meansafter the pattern light has been reflected by said reflecting surfaceand returned through said soft contact lens; and said pattern lightprojecting optical system and said light receiving optical system sharea part of respective optical portions and a deflecting member fordeflecting and projecting the pattern light with respect to an opticalaxis of said pattern light projecting optical system is provided in saidshared portion.
 40. A refractive power measuring apparatus as claimed inclaim 10, wherein: said measuring optical system has a pattern lightprojecting optical system for projecting the pattern light onto areflecting surface through said soft contact lens; said light receivingelement is provided in a light receiving optical system, said lightreceiving optical system being for conducting the pattern light to thelight receiving element after the pattern light has been reflected bysaid reflecting surface and returned through said soft contact lens; andsaid pattern light projecting optical system and said light receivingoptical system share a part of respective optical portions, and adeflecting member for deflecting and projecting the pattern light withrespect to an optical axis of said pattern light projecting opticalsystem is provided in said shared portion.
 41. A refractive powermeasuring apparatus as claimed in claim 40, wherein said deflectingmember is a deflecting prism which is rotated about the optical axis ofsaid pattern light projecting optical system.
 42. A refractive powermeasuring apparatus as claimed in claim 40, wherein said deflectingmember is disposed at a position not conjugated with the disposedposition of said soft contact lens in measuring optical characteristicsof the soft contact lens.